Not that this analogy has any real meaning anyway, but it's not illegal to enter an unlocked house. That's why the crime is called "breaking and entering". Entering in and of itself is not a crime. There was a burglar who, before actually taking anything, was caught. He actually was acquited because the mat said "Welcome" and his argument was that he was just wandering by and no one responded to his knock. Some or most localities have ordinances about peeping toms and such but they may or may not be relevant to this particular act and it may not actually be illegal to enter the house. Entering the house and turning on the TV, though might be. I agree, though, with the other respondents: these are public airwaves and you certainly can't proceed with any expectation of privacy.

Just another 2c...